Compared to other races/ethnicities, African Americans with HIV have lower levels of engagement in care, are less likely to be on antiretroviral treatment (ART), and are more likely to delay care and ART initiation; those on ART are less likely to be adherent at high enough levels for the treatment to be effective. We propose to test an innovative, culturally relevant treatment advocacy (TA) intervention for African Americans with HIV that targets social and cultural issues contributing to poor HIV treatment behaviors. TA, which has been sustained in many community organizations throughout the HIV epidemic, has never been systematically evaluated. TA facilitates patient navigation through the medical system and provides tailored HIV treatment education and client-centered counseling to improve adherence and engagement in care. TA targets social and contextual issues in healthcare and patients' lives by advocating to providers to improve patient-provider relationships, recommending changes in treatment and/or providers (if needed), and referring patients to mental health and social services. TA is particularly appropriate for African Americans with HIV, who may be mistrustful of providers: it can be conducted outside of the medical system in a safe, neutral community setting by individuals not associated with patients' healthcare. We developed a culturally relevant TA program that additionally discusses factors such as racism that undermine healthcare in Black communities, by acknowledging and directly addressing patients' medical mistrust and stigma as coping strategies that arise in response to oppression. The specific aims are to (1) conduct a randomized controlled trial to examine the effects of a culturally relevant TA program on adherence among African Americans with HIV; (2) identify culturally relevant mediators that explain the effects of treatment advocacy on antiretroviral treatment adherence among African Americans with HIV (e.g., improved behavioral adherence skills, coping with stress/discrimination, mental health, and patient satisfaction; lower levels of HIV misconceptions, internalized HIV stigma/homophobia, medical mistrust, and substance use); and (3) explore culturally relevant moderators of the effects of treatment advocacy on antiretroviral treatment adherence among African Americans with HIV (e.g., discrimination, incarceration, poverty, social support, spirituality, trauma). A sample of 200 African Americans with HIV will be randomly assigned to a TA intervention or wait-list control group. Participants will complete surveys at screening, and at 3- and 6-months post-baseline, to assess pre-, intra-, and post- intervention effects on adherence.